Not Applicable.
1. Field of the Invention
This invention relates to forestry equipment, and in particular to control of a feller buncher.
2. Background of the Invention
Feller buncher heads are widely used in the logging industry for accumulating in a vertical position several freshly cut trees prior to laying down the bundle at once, to be transported to roadside by a skidder or forwarder. The felling head is mounted to a heavy duty vehicle, such as a drive to tree or swing to tree wheeled or tracked vehicle, for high efficiency logging.
A feller buncher head may use a saw blade disc, a shear, or other means for severing the tree. FIGS. 1-3C illustrate a typical disc saw feller buncher 10. After severing, each tree is added to the bundle already cut which is supported on a butt plate of the head and held in place by a pivotable hydraulically operated accumulator arm 16. As the tree is cut, it is typically stabilized by one or more pivotable hydraulically operated harvesting arms 18. Typically, as illustrated, two harvesting arms 18 are provided which move in unison, are vertically spaced apart and are hinged to the frame 20 of the head to pivot about a vertical axis on one side of the frame. A single accumulator arm 16 is typically provided, positioned vertically between the two harvesting arms 18 and hinged to pivot from the opposite side of the frame 20.
When the cut of the first tree T1 is completed, the accumulator arm 16 is actuated by extending a hydraulic cylinder 22 (FIG. 3A) to hold the tree in the side pocket position shown in FIG. 3B, where the butt end of the tree is trapped against the pocket walls 39 and the upper part of the trunk is trapped against the fixed upper arms 41, also known as the horn. After the next tree T2 is cut (FIG. 3B), harvesting arms 18 are actuated by extending another cylinder 22 (illustrated in FIG. 1) to pull the tree into the pocket while at the same time actuating the arm 16 to withdraw it from the bundle and bring it back around the bundle including the newly cut tree (see FIG. 3C). The several operations of the hydraulic cylinders 22 are typically manually performed separately, and, although the operations are repetitious, it requires considerable skill to efficiently cut, accumulate and unload trees. Thus, improvement is needed to perform these operations.
Automatic felling head control according to the present invention decreases the amount of manual clamp functions during felling and accumulating operations. Instead of operating clamps separately using manual clamp buttons, the accumulator and harvesting clamps are operated as a system.
A felling head control of the invention preferably uses a microprocessor based controller to operate the felling head clamps automatically during felling/bunching operations. The felling head can be controlled by the operator with just two actuators, for example, buttons; one to collect trees and the other to dump bunches. Each actuator controls at least one function of each of the accumulator and harvesting clamps. Manual control buttons are also available in parallel to the automatic control.
When cutting trees with manual control, each accumulated tree usually requires four buttons to be pressed (harvesting clamps closexe2x80x94accumulator clamps openxe2x80x94accumulator clamps closexe2x80x94harvesting clamps open). In addition, all the buttons have to be held down as long as the clamp movement is required. Clamp automation reduces the amount of button activation according to the following calculations (numbers indicate how many buttons have to be pressed to make bunches using different methods):
The above table shows that automatic control according to the invention reduces button operations 50-70%. The system will become more effective as bunch size grows. In addition the buttons do not have to be pressed for the entire duration of the movement, only a short pulse is required.
If a felling head is accumulating trees normally, automated operation according to the invention is as or more efficient as the manual method, and helps to reduce operator fatigue considerably.
In one aspect of the invention, when an actuator of the system is actuated for a first tree, the control system closes a harvesting clamp and an accumulator clamp, and then re-opens the harvesting clamp. This automates the cutting and accumulation of the first tree, and readies the machine for the next tree. Preferably in this aspect, the actuator can also be actuated to close both clamps and hold them closed, for example by holding down the actuator for an extended period. This would be used when cutting the last tree.
Preferably, when the actuator is actuated for a second tree being accumulated, the control system closes the harvesting clamp, opens the accumulating clamp, re-closes the accumulating clamp and re-opens the harvesting clamp. This control sequence replaces several steps in comparison to manual operation of the clamps. In addition, in this connection, an advance may be provided, so that the accumulating clamps start to open before the harvesting clamps are completely closed.
It is also preferred that the control system is programmable, and preferably by the operator him or herself, so that advance and delay times can be adjusted in the field for the most efficient operation of the machine.
In another preferred aspect, a second actuator is provided which when actuated opens both of the clamps. This is used for dumping the trees and to reset the system for the next bundle. It is also preferred to provide a third actuator, which when actuated stops all clamp functions.